Childhood leukemia survival climbed from under 10 percent to 90 percent
In the 1960s, fewer than one child in ten survived acute lymphoblastic leukemia. By 2015 about nine in ten did. It is the most common childhood cancer in the United States, and it holds a quiet distinction in medical history as the first cancer that had spread through the body to be cured.
Acute lymphoblastic leukemia, or ALL, begins with the lymphoblast, an immature cell that should grow into an infection-fighting B or T lymphocyte. The body normally regulates how many of these cells it makes. In ALL, one lymphoblast accumulates many mutations affecting development and division, and the resulting clone floods the system with immature cells. Left untreated, the disease moves fast, usually proving fatal within weeks or months. In 2015 it affected about 876,000 people worldwide and caused about 111,000 deaths, striking children aged two to five most often.
Early signs are vague, particularly in children. Among young patients, more than half showed at least one of five features: an enlarged liver or spleen that could be felt, pale skin, fever or bruising. Tiredness, bone and joint pain from blast cells reaching the bone surface, swollen lymph nodes and tiny red skin spots caused by low platelets are also common.
In most cases no cause is found. The emerging picture for childhood cases is a two-step process: a child inherits some risk variants in genes such as ARID5B, IKZF1 or GATA3, each individually weak, and later exposures push developing cells to acquire more mutations. Uneven spread of such variants may help explain why rates differ between ethnic groups. Fewer than 5 percent of cases are tied to known syndromes such as Down syndrome. Infant ALL, in babies under a year old, is different: a rearrangement of the KMT2A gene arises before birth, and usually only one more mutation is needed.
Environmental links remain contested. Heavy radiation such as nuclear fallout is a known risk, while evidence on low-dose sources like X-rays in pregnancy or power lines shows at most slight increases. Treatment typically starts with chemotherapy to achieve remission and continues for years, including doses delivered into the spinal fluid, because the central nervous system is a common hiding place for relapse. Engineered immune cells known as CAR T cells are under further study.
Source: Acute lymphoblastic leukemia
